4.
CHERIAN VARGHESE
Prevalence and Determinants of
Human Papillomavirus (HPV) Infection
in Kerala, India
ACADEMIC DISSERTATION
To be presented, with the permission of
the Faculty of Medicine of the University of Tampere,
for public discussion in the auditorium of
the School of Public Health of the University of Tampere,
Medisiinarinkatu 3, Tampere, on May 26th, 2000, at 12 o’clock.
U n i v e r s i t y o f Ta m p e r e
Ta m p e r e 2 0 0 0

8.
1 INTRODUCTION
Human papillomavirus (HPV) is the major etiological agent for cervical cancer, the
second most common cancer among women everywhere in the world (Munoz et al.
1994). This virus is also implicated in other anogenital cancers. HPV is among the most
important viruses in the causation of cancer and a large number of epidemiological,
biological and clinical studies are underway to get to know the nature of this infection
and its outcomes. The prospects of HPV vaccine in preventing cervical cancer makes it
the most suitable target for studies in low resource settings with high morbidity and
mortality from cervical cancer.
Papillomaviruses are non-enveloped, double stranded DNA viruses that are
included in the papaovaviridae family and multiple types have now been identified.
More than 85 well characterised genotypes are recognised, and more than 120 have
been tentatively identified (zur Hausen 1999). Human papillomaviruses are associated
with benign and malignant lesions of the anogenital tract and cause genital and foot
warts. These viruses show tissue specificity and variable malignant potential.
Sexual behaviour, mainly age at first intercourse and multiple sexual partners
have been consistently reported as risk factors for invasive cervical cancer. These
epidemiological characteristics are consistent with a sexually transmitted disease. Once
HPV has been identified, most of the known risk factors for cervical cancer appeared as
surrogates for this infection.
The prevalence and determinants for HPV infection in general populations has
been addressed in a few studies (Becker et al. 1991, Van Den Brule et al. 1991). It is
important to address HPV epidemiology in general populations especially in low
resource countries with a high incidence of cervical cancer, as it will provide
information for the prevention and control of this cancer.
1.1 Cervical cancer control in Kerala
The state of Kerala on the south western coast of the Indian Union has achieved
considerable progress in the health sector which is reflected in the low infant and
maternal mortality rates and higher life expectancy compared to the country as a whole
(Table 1). The life expectancy at birth was 67.0 years among males and 72 years among
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Table 1. Demographic data and vital statistics of Kerala and India in 1995.
_____________________________________________________________________
India Kerala
_____________________________________________________________________
Density of population/Sq Km 267.0 749.0
Annual popn. growth rate % 2.2 1.3
Birthrate/1000 27.2 17.9
Deathrate/1000 8.9 6.2
Infant mortality rate/1000 LB 71.0 12.0
Literacy male % 64.1 93.6
Literacy female % 39.3 86.2
Life expectancy male 60.6 67.0
Life expectancy female 61.7 72.4
_____________________________________________________________________
LB live births, popn. population
females in 1995 in Kerala (Economic Review 1996). This demographic transition has
already taken place in the Western countries of the world. Need-based planning within
the limited resources is essential to control the emerging epidemic of chronic diseases
like cancer and cardiovascular diseases in Kerala.
Lack of reliable data on the magnitude of chronic diseases in India has been a
major limitation in assigning their priorities in health care and medical research. This
prompted the Indian Council of Medical Research to launch the National Cancer
Registry Programme (NCRP) in 1981, by which seven population based cancer
registries have been established in various parts of the country so far. The pattern of
cancer in India shows a predominance of tobacco related cancers in men. In women the
cervix and the breast were the most common sites of cancer (NCRP 1992).
India is one of the few developing countries that have formulated a National
Cancer Control Programme (NCCP 1984). The programme envisages control of tobacco
related cancers, early diagnosis and treatment of uterine cervical cancer and distribution
of therapy services and palliative care through augmentation of health infrastructure.
Suggested surrogate outcome measures include change in tobacco use, the 'Knowledge,
Attitude, Practice' (KAP) pattern, compliance to screening programmes, changes in
referral practices and shift in stage distribution (Sankaranarayanan et al. 1992).
The Regional Cancer Centre, Trivandrum (RCC) has developed a feasible and
sustainable community based cancer control programme in Kerala, and has been
designated as the “WHO Collaborating Centre for Cancer Control in Developing
Countries”. The RCC is the seat of a hospital based cancer registry, which is responsible
for cancer registration from hospitals under Trivandrum medical college besides the
RCC. These data have been the main resource for initiating cancer control programs in
Kerala.
Population based cancer incidence data were available in Kerala from the
Trivandrum and Karungappally registries (PBCR 1999, NBRR 1997). Besides these a
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large number of epidemiological studies are being conducted by the RCC. Risk factors
for common cancers in the hospital cancer registry were reported (Sankaranarayanan et
al. 1994).
The age adjusted incidence rate for uterine cervical cancer in Trivandrum was
15.5 per 100,000 in the period 1991–92 (Parkin et al. 1997). Based on this, it is
estimated that on an average 2,500 to 3,000 new cases of cervical cancer would occur in
Kerala annually. Data from the Hospital Cancer Registry in Trivandrum reveal that
more than 50% of cervical cancers present in FIGO stage III, and this is reflected in an
overall 5-year survival rate of 47% (Sankaranarayanan et al. 1995).
Pap smear based cytology screening has been the recommendation for the
prevention of invasive cervical cancer and several agencies and countries have accepted
this strategy. The effectiveness of organised cytology screening programmes has been
well demonstrated by the Finnish mass screening system. The incidence of cervical
cancer in Finland decreased from 15/100,000 in 1963 when screening was introduced to
2.5/100,000 in the mid 1990’s (Hakama et al. 1991). Countries with limited resources
are finding it difficult to establish organised screening programmes and alternative
strategies like ‘visual examination’ have been proposed. These approaches have not
been found to be useful (Wesley et al. 1997). Improvements in living standards and
empowering women are the prerequisites for cervical cancer control in India (Varghese
et al. 1999).
Prevalence of HPV has largely been studied among cervical pre-cancerous lesions
and in cervical cancer. It is important from the public health and preventive aspects to
study the prevalence and identify the determinants of HPV infection, which will offer
the potential for primary prevention and newer methods of screening and vaccination.
With this background a study was carried out in the suburbs of Trivandrum, the
capital of Kerala State, to address the prevalence and determinants of Human
Papillomavirus. This dissertation will present the organisation of the cohort, and
prevalence and determinants of HPV infection and discuss the implications of these
results.
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2 AIMS OF THE STUDY
1) To study the prevalence of uterine cervical Human Papillomavirus infection among
married women in a general population in Kerala, India.
2) To study the determinants of uterine cervical HPV infection in this population.
3) To consider the implications for control of HPV infection and cervical cancer.
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3 REVIEW OF THE LITERATURE
3.1 Human Papillomavirus
Beral (1974) postulated that exposure to sexually transmitted infection is an important
determinant of cervical cancer. zur Hausen (1991) suggested that HPV infection and
HPV viral gene expression have emerged as necessary, but not sufficient factors for
cancer induction. Reviewing the epidemiological evidence linking HPV to cervical
cancer, Bosch et al. (1997) concluded that over 90% of cervical cancers could be
attributed to certain HPV types. The central role of HPV in cervical carcinogenesis has
far-reaching implications in the prevention of this cancer.
Molecular Virology of HPV
HPV is a small, double-stranded DNA virus that is a member of the papovavirus group.
The subtypes of HPV are not serotype viruses but are genotypes in which the typing
scheme is based on the similarity of one HPV type to the other known HPV types at the
DNA level. The central HPV-DNA repository is in Heidelberg and this facility assigns a
new type of HPV after adequate studies. The viral genome of HPV consists of
approximately 7900 nucleotides, and all viral gene transcription occurs off one strand.
The HPV genome may be divided into three parts based on the function of the
encoded genes: the early (E) region E6, E7, E1, E2, E4 and E5 and the late (L) region
L1, L2 and L3 and a non coding region which harbours the origin of replication and
transcription control signals essential for the regulatory functions of the genome (Fig.1).
E6
LCR
E1
7905
L1
E2
L2 E4
E5
Figure 1. HPV genome – schematic representation.
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HPV genome is approximately 7900 bp in length. The early (E) region of the
genome is separated from the late (L) region by the long control region (LCR) that
contains sequences involved in the regulation of expression of HPV proteins.
The viral genomic DNA in fully formed viral particles is surrounded by a protein
coat known as the viral “capsid” that consists of the (L) regions L1 and L2. The (E)
region proteins are associated with cell transformation and viral gene regulation and are
most critical in the pathogenesis of invasive cancer. Between (E) and (L) lies the LCR,
which contains promoter and enhancer DNA sequences critical to viral gene
transcription by both viral and cellular genes.
The specific HPV types exhibit a degree of tissue tropism. Some types such as
HPV 1 and 2 are most found in the keratinized skin of the palms and soles in the form
of plantar and palmar warts. Types such as 6,11,16 and 18 are most often found in the
keratinized skin and mucosal surfaces of the anogenital region, including the cervix.
Types 16 and 18 are considered to have a ‘malignant’ phenotype as they exhibit a strong
association with invasive cancer (Palefsky and Holly 1995).
Detection of HPV infection and HPV genotypes
Reliable and reproducible measurement of ‘exposure’ is an important aspect of
epidemiological investigations. In studying the relation between HPV and cervical
neoplasia, it is not always possible to obtain tissue biopsies. A cytological finding of
koilocytosis represents HPV infection but cytology cannot detect the large percentage of
infections at the DNA level. A major limitation of earlier epidemiological studies was
the lack of an appropriate method for assessing type specific HPV infection.
Serological methods were also used to study the HPV infection. Sero-reactivity to
HPV is a a reflection of the cumulative exposure to HPV. It is also useful to use
serological methods to study the transmission of HPV. High risk of seropositivity to
HPV 16 with multiple sexual partners has been shown in studies (Oslen et al. 1997).
The techniques of Southern, dot-blot and ‘filter in situ’ hybridisation have
suffered from problems of sensitivity and specificity, particularly when DNA extracted
from cervical smears was examined (Munoz et al. 1988). The Polymerase Chain
Reaction (PCR) is an in vitro method for primer directed enzymatic amplification of
specific target DNA sequences (Saiki et al.1988). PCR generates millions of copies of a
specific DNA fragment in a few hours by in vitro enzymatic synthesis. HPV–PCR
consists of amplification of a targetted portion of the viral DNA and identification of the
amplified product. PCR has been extensively used for HPV identification from
exfoliated cells and biopsy tissues and for facilitating cloning and sequencing of HPV
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genomes. Stringent measures have to be adopted to avoid contamination of the
specimen for PCR diagnosis. PCR has been shown to be more sensitive than Filter in
situ Hybridisation and Southern Blot analysis in the detection of HPV in cervical
scrapes (Melchers et al. 1989).
3.2 Risk factors for HPV infection and persistence
The prevalence rates of HPV in the general population is available mainly from the
Western world. A study in New Mexico has found a prevalence of 9% among the
general population. The prevalence rates were 13.7% for non-Hispanic white women,
9.7% for Hispanics and 6.6% for Native American Women (Becker et al. 1991). The
International Agency for Research on Cancer (IARC) surveys of HPV prevalence in
general populations have been presented recently. The prevalence varied from 8% in
Thailand to 17% in Colombia. The overall prevalence was found to correlate roughly
with the risk of cervical cancer in the population (Munoz et al. 2000).
The risk factors for cervical cancer may be those that are risk factors for HPV
infection as well. Kataja et al. (1993) reported a case-control study of risk factors for
HPV infection in Kuopio, Finland. The risk of infection varied with age, being the
highest in the age group 20–29 years, and thereafter declining over the years. Number of
sexual partners in the past two years was the most significant independent risk factor
(adjusted OR 12.1). Current smoking, warts in sexual partner and frequency of sexual
intercourse were identified as independent risk factors for HPV infection. This study
also suggested that sexual intercourse was the main form of HPV transmission.
Risk factors for HPV infection were studied (Sexually Transmitted Disease clinic
based study) in two areas with different cervical cancer incidence (Greenland and
Denmark) by Svare et al (1998). The HPV prevalence among women declined after the
age of 20 years in Greenland compared to Denmark, where the decline was after the age
of 30 years. Age at first intercourse was not associated with HPV infection in either
region. In Greenland those subjects who had had their first intercourse within 4 years
prior to the study had a risk of 139.2 (95% CI 5.3–367.6) compared to those whose first
sexual intercourse had occurred 15 years previously. The risk of HPV increased with
increasing number of sexual partners. The number of sexual partners within the last year
showed a strong association with HPV infection. Ley et al (1991) have reported that
HPV infection was strongly and independently associated with increasing number of
sexual partners in a lifetime, use of oral contraceptives, younger age and black race.
Positive associations with lifetime number of sexual partners, socio-economic status,
and Chlamydia trachomatis and HPV infection has been reported (Munoz et al. 1996).
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A strong association of high risk HPV DNA and HIV-1 sero-positivity has been
reported suggesting the role of immunosupression in the occurrence of HPV (Piper et al.
1999).
Most of the HPV infections are transient and the persisatnt infections are
important events. It has been shown that type-specific persistent HPV infection,
particularly with a high viral load, produces chronic cervical dysplasia (Ho et al. 1995).
Hildesheim et al. (1994) had reported type specific persistance of HPV in 41% over a
median follow up of 14.9 months. Age above 30 years and infection with high risk types
were found to be more likely to persist. Factors associated with persistence of HPV
infection were addressed by Brisson et al. (1996). Among 179 women who were HPV
positive, 50.8% had persistent infection after a mean follow-up of 11 weeks. The factors
associated with persistence of HPV were young age (< 25 compared to >25 years),
lifetime number of sexual partners, and use of oral contraceptives. Among women who
had had more than 8 partners, HPV infection persisted in 66.7% compared to 17%
among those who reported one partner. Infection among those with high-risk HPV types
(16,18,31,33,35) and high viral load at initial examination was more likely to persist
than low risk types. Age at first intercourse, number of pregnancies, history of
gynaecological infection, condom use, smoking and alcohol drinking were not
associated with persistence of HPV infection.
3.3 Aetiology of cervical neoplasia
A review of epidemiological studies by Rotkin (1973) revealed that the incidence of
carcinoma of the uterine cervix was higher in women of lower social class, those with
many pregnancies, with a young age at first marriage, and in those with multiple sexual
partners. These factors point towards the likelihood for a sexually transmittable agent in
the aetiology of carcinoma of the cervix.
An increase in the incidence of cervical cancer among the younger age groups in
certain regions had been linked to HPV and some concern was raised about the
emergence of adenocarcinoma of the cervix (Zheng et al. 1996).
Murphy et al. (1992) reported that the social class difference in incidence of
cervical cancer was present in all age groups and that this could not be explained by the
gradient of social class on the attendance rate of cervical screening. It is possible that
factors other than compliance with screening are operating in the lower social class. The
religious practice of circumcision of males was considered as a protective factor among
Jews and Muslims (Brinton and Fraumeni 1986).
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Sexual behavioural characteristics, particularly young age at first intercourse and
multiple sexual partners have been consistently reported as risk factors for invasive
cervical cancer and pre-cancer (Cuzick et al. 1989, Jussawala et al. 1971, Parazzini et al.
1992, Bjorge and Kravdil 1996, Kvale et al. 1988). The role of a male factor in cervical
cancer was noted from the studies showing geographic clustering of cervical cancer and
penile cancer (Li et al. 1982). Risk of cervical cancer was found to be increased
significantly in women whose male partners have reported multiple partners (Brinton et
al. 1989). Beral et al. (1988) reported a significantly higher incidence of cervical cancer
among oral contraceptive users compared to never-users in a cohort study. Juneja et al.
(1995) have observed age below 18 years at consummation of marriage and
multiplicity of sexual partners as the independent risk factors in Indian women.
Smoking also had been considered as a risk factor for cervical cancer
(Winkelstein 1977). However in India, which is a high incidence region for cervical
cancer, tobacco smoking in women is extremely rare.
Bacterial vaginosis is a common problem in un-screened women. In bacterial
vaginosis, the lactobacilli-dominated flora is replaced by an abundant complex flora,
constituted by gardenella, micrococci, streptococci and staphylococci. The abnormal
vaginal flora can produce carcinogenic nitrosamines and may contribute to cancer
(Frega et al. 1997).
Etiological role of HPV
Experimental studies have provided strong evidence that HPV is the long sought
venereal cause of cervical neoplasia. A series of epidemiological studies with adequate
exposure measurement in different settings has confirmed this finding (Munoz et al.
1994).
Prevalence of HPV DNA ranging from 22% to 100% have been reported in case
series from different settings (IARC 1995). This broad range is considered to be due to
variations in the methods used for HPV detection. Bosch et al. (1995) carried out a
worldwide prevalence study of HPV in cervical cancer in 1995. More than 1000
specimens from 22 countries were studied. HPV DNA was detected in 93% of tumours,
with no significant variation in HPV positivity among countries. HPV 16 was present in
50% of the specimens and HPV 18 in 14% of specimens. These results confirmed the
role of genital HPV in the causation of cervical cancer. The etiological role of HPV and
other risk factors in precancerous lesions of the cervix has been reviewed by Murthy
and Mathew (2000).
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Case-control studies showed that the prevalence of HPV infection among cases
was very high, which resulted in high odds ratios not usually seen in epidemiological
studies. The classical risk factors have lost their significance in most studies when
adjusted for HPV status (Hernandez et al. 1997, Eluf Neto et al. 1994, Munoz et al.
1992, Peng et al. 1991, Reeves et al. 1989).
The majority of the prospective studies have established a substantial excess risk
for progression to higher grades of cervical precancerous conditions among those who
were HPV positives and more so for high risk HPV types (Campion et al. 1986, Ho et
al. 1998, Remmink et al. 1995).
Presence of HPV antibodies in serum was associated with an odds ratio of 13.2
for invasive cervical cancer and this was significant (Lehtinen et al. 1996). After
adjustment for smoking and antibodies to other sexually transmitted agents the risk of
HPV infection remained significant with an odds ratio of 12.5. Ferrera et al. (1997) have
reported similar findings in a study in Honduras. After adjusting for other sexually
transmitted infections, presence of HPV16 anti E7 emerged as the significant risk factor
for cervical cancer with an odds ratio of 3.6. In a prospective sero-epidemiological
study, Dillner et al. (1997) reported an excess risk for past infection with HPV 16 for
invasive cervical cancer.
3.4 HPV in the natural history of cervical neoplasia
Cervical carcinogenesis passes through well-defined entities as the changes occur in the
epithelium. The age specific incidence of cervical dysplasia shows that it was most
often diagnosed among women in their 20’s, carcinoma in situ (CIS) among those aged
30 to 39 years and invasive cancer after the age of 40 years (Canadian Task Force
1976). Each non-invasive type can regress to normal, progress to the next level of
dyplasia or progress to invasive cervical cancer. The age specific incidence rates of
preinvasive lesions are not usually collected. This information was available in
Denmark on a population level, which showed that the distribution of mild, moderate
and severe dysplasias and of CIS have the same shape as a function of age. The
sequence in time at which they attain the peak supported the successive progression
(Storm et al. 1989).
Koutsky et al. (1992) did a prospective study on 241 women with baseline HPV
status and other risk factors. The cumulative incidence of cervical intraepithelial
neoplasia grade II or III was 28% among women with a positive test for HPV and 3%
among those without detectable DNA. The risk was highest among those with HPV
type 16 or 18 infection. In four years, the infection progressed among 56% of those who
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were HPV positive compared to 25% of the negative subjects. In a prospective study of
95 women with cervical intraepithelial neoplasia (CIN I). Downey et al. (1994) did not
find any excess risk of progression in those who were positive for HPV. They suggested
that a histological diagnosis of low-grade cervical disease was a better long term
predictor of disease progression than HPV positivity. Rozendaal et al. (1996) have
tested the value of a PCR based test for high risk HPV types in a cohort of 1622 women
with a follow-up of 40 months. The outcome was CIN III. Those women with high risk
HPV types and normal Pap smear were 116 times more at risk of developing CIN III
compared to women without high risk HPV. In a follow up study of Finnish females,
Syrjanen et al. (1990) have reported a prevalence of HPV infection of 3% at the
beginning of the follow up and 7% one year later. They estimated that up to 79% of the
Finnish females would contract at least one HPV infection between ages 20 and 79
years. They suggested that the progression of precancer to invasive cancer was
regulated by factors not clearly delineated at that time.
The prevalence of HPV infection (detected in cervical epithelium) declines with
age, while cervical cancer prevalence rises with increasing age. However the HPV
antibody level in the serum shows a steady increase. The role of HPV in the natural
history of cervical cancer has been suggested to be mediated through the proteins E6
and E7. The protein E6 transforms cells by binding the cellular tumour suppresser and
regulatory protein p53, leading to rapid degradation of p53. This results in chromosomal
instability and aneuploidy. The E7 protein binds and phosphorylates the retinoblastoma
protein (Rb) and leads to activation of mitosis (Werness et al. 1990).
3.5 Prospects of HPV testing in screening and vaccination
against HPV
Anogenital warts are caused by HPV and many methods are available for their
treatment. Patient administered topical therapies and provider-administered cryotherapy,
interferon and surgery are the current practices. In the uterine cervix the HPV infection
is treated as part of the treatment of cervical precancerous lesion (Beutner and Ferenczy
1997). Even in countries with organised screening programmes and adequate resources,
treatment of asymptomatic HPV infection remains an important issue.
Cuzick et al. (1995) tested for HPV in women who were attending a screening
programme in England. They found that 44% of the cervical intraepithelial neoplasia of
grade II/III proven by HPV typing had negative cytology. The positive predictive value
for HPV testing was 42%. HPV types 16 and 31 were found to be the most specific.
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They suggested that HPV testing could usefully augment but not replace the
conventional cytology.
Galloway (1998) presented the features that make HPV amenable to vaccination.
The predominant genital types are conserved globally, and the viral genomes are not
prone to mutation because HPV uses the cellular replication machinery. There are only
eight viral genes and this limits the complexity of the immune response. Animal models
of therapeutic vaccines have been found to be feasible.
Luostarinen et al. (1999) have shown that women who harbour both HPV 6/11
(low risk types) and HPV 16 do not have an increased risk for cervical cancer. The HPV
specific immunity provided by the coexisting low risk types might have provided the
protection from the high risk types. This finding supports the prevention of squamous
cell carcinoma of the cervix by vaccination. A study of eight patients with advanced
cervical cancer vaccinated for HPV was reported by Borysiewicz et al. (1996).
Vaccination resulted in no significant clinical side effects in the women. HPV specific
antibody response (HPV specific cytotoxic T lymphocytes) was detected in one out of
three evaluable patients. Clinical trials are in progress for therapeutic vaccines.
The availability of a vaccine for HPV might help to prevent cervical cancer in the
future. Meanwhile established methods of cervical control have to be provided for the
women at risk, especially for the poor and vulnerable sections of society in low resource
countries. Epidemiological studies are needed in these countries to study the occurrence
and determinants of HPV infection, which is the most important etiological agent for
cervical cancer.
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4 SUBJECTS AND METHODS
Prevalence of HPV was studied in the general population in a defined geographical area
by establishing a cohort of married women. This cohort provided the framework for
addressing the determinants of HPV infection.
The study was conducted in two suburban regions of Trivandrum District viz.
Kazhakuttom Panchayat (one of the administrative units) and Maryandu village, (15
Kilometres away from the Regional Cancer Centre) (Figure 2). Kazhakuttom Panchayat
was selected for operational and logistic convenience as well as for the fact that this
area had a good representation of the three major religious groups in Kerala. Maryanadu
village is an area where we had conducted field studies earlier and hence had a logistic
advantage. The Panchayat consisted of 10 wards, which were subjected to repeated
changes in their composition, based on the definitions for the electoral constituencies
(Figure 3). The addresses of all the households in these regions were available at the
Panchayat office (administrative office), the reliability of which was not certain. It was
known from the official records that there were about 6000 households.
Pilot phase
A pilot study was conducted between March and August 1993 to assess the feasibility.
The list of houses maintained in the Panchayat office was utilised to identify the eligible
population during the pilot phase. Clinics were held at the field office, in Kazhakutam.
Attendance at these clinics was not restricted to any defined population and women
from outside the study area also visited the clinic. One thousand six hundred samples
were collected during this period, of which 1295 samples were from the eligible
subjects (20% were from outside the study area). It was realised from the pilot phase
that the list of addresses in the administrative office was not adequate and unique
identification of an individual was not possible. Hence, considering the logistic aspects,
the study was conducted in the following way.
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4.1 Organisation of a cohort
A team of staff was recruited (medical officer, sociologist, cytotechnologist, cyto-
technician, field workers, data entry clerk, office clerk, driver and helpers) in November
1993. The various questionnaires, household form, individual form, consent forms in
local language and cytology forms to be used in the study were finalised, incorporating
the experience of the pilot phase.
A complete survey of the households was undertaken in the study area to establish
a cohort. Information was collected on a household survey form (Appendix 1), which
contained details of the ownership of the house, members of the household, their age,
marital status, and relationship to the head of the household. Maryanadu, a Catholic
fishing village, is a settlement in makeshift, thatched huts on the beach. Women of this
village were identified by the local field worker through the parish list, and the list of
the social services organisations in the village.
The enumeration of the entire study area took 9 months to complete and details of
all the households were entered into the computer. From this database, all married
females who were permanent residents of the area were identified as the potentially
eligible population. Each of them was given a unique identification number, which
consisted of the ward number, house number and the individual number within the
household. This unique identification number was used in all the forms and data entry
programmes for linkage purposes. Women were given an identity card with this number
(Appendix 2).
4.2 Awareness programmes
There had been no previous screening programmes for cervical cancer in the study area
and the local health programmes were focussed on maternal and child health and
immunisation. The help of voluntary organisations and women’s groups was solicited to
conduct awareness programmes in the community. Thirteen community seminars were
organised in the study area. Pamphlets describing the study and the procedures were
distributed through various local groups (Appendix 3).
All religious organisations and political parties were approached to gain the
confidence of the community. Both women and men were invited to the awareness
programme. Men’s participation was essential, as women have to get their permission to
attend the clinics. The content of the awareness programmes included information on
cancer, its warning symptoms in general and cervical cancer prevention in detail. The
female medical officer explained about the procedure for smear taking. The community
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was assured that appropriate treatment and follow-up for those with abnormalities
would be provided at the RCC, Trivandrum.
4.3 Field clinics
Clinics were initially held in Government health centres. These centres were sometimes
situated at places remote from where the people resided and women were not happy to
walk long distances to attend the clinic. In order to make it convenient, field clinics
were organised. Two weeks before the clinic, the sociologist would identify the women
to be invited from the computerised list. The social workers would then visit these
households and personally invite the women.
Women were more likely to attend a programme in their vicinity without missing
their daily household chores. Government buildings and private households were used
for conducting the clinics. The team from RCC would reach there sufficiently early and
arrange the furniture and electricity supply. Transportation was arranged to bring the
older women who did not care to walk.
Medical consultation
The medical officer of the team provided prescriptions for the women and sometimes
for the family members who accompanied these women. The medical officer was
available in the field office every day and women were asked to see the doctor if they
had any complaints.
Data collection
Women who attended the clinics with their identification cards were matched with the
computer list. The rest of them had to be checked by name and address through the lists
in the clinic to make sure that they belonged to the cohort. An informed consent form
in vernacular (Appendix 2) was given which explicitly mentioned the biological sample
collection. After obtaining an informed consent, the social worker interviewed them to
collect data on socio-demographic details, marital and reproductive factors and
gynaecological symptoms (Appendix 4). Gynaecological symptoms and temporary
contraceptive measures were asked over a reference period of one year.
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A questionnaire on sexual behaviour was introduced after the completion of the
first year of study. This was mainly due to logistic reasons as such a questionnaire in the
beginning would have been difficult to administer. The female medical officer and the
sociologist interviewed women in the privacy of the clinic. Information on multiple
sexual partners and other sensitive questions were included in this interview schedule
(Appendix 5). Questions on genital hygiene were asked to reflect the usual practise.
Men were not available to be interviewed and their behaviour was also enquired from
their wives.
Data collection from the field was through interviews and interviewers assessment
of the responses were considered for data quality. Given the nature of the details
collected, repeated questioning was not feasible. The HPV status was not known at the
time of the interview. Range checks were introduced at the time of data entry.
4.4 Biological sample collection
A female cytotechnician took the Pap smear using an Ayer’s spatula from the cervix.
The first sample from the spatula was dissolved in a phosphate buffered saline solution
and placed in ice packs immediately. The next sample was smeared onto glass slides,
which were marked with the unique identification numbers. The samples were taken to
RCC. The cell samples were separated into three aliquots, numbered and stored in –40o
Centigrade freezers. Cytology smears were received in the cytopathology division for
staining and reading.
HPV testing
The cell samples in deep freezers were transported to the UK for HPV testing. The
samples were carried in dry ice to preserve the cells. However a few of them perished in
transit. PCR analysis of cervical cell samples was undertaken in the dedicated
laboratory facilities at the Institute of Cancer Research, set up according to
recommended anti-contamination procedures (Bauer et al. 1992). The results of these
analyses were then linked to the database on interview schedules using unique
identification numbers.
Samples were thawed at room temperature and resuspended. The cell pellets
obtained from centrifugation of 250µl of each sample were resuspended and digested by
incubation at 55°C for 1 hour in 25µl of 50mM Tris-HCl buffer (pH8.5) containing
1mM EDTA (TE buffer), 1% (v/v) Tween-20 and 200µg/ml proteinase K. The protease
25

25.
was inactivated by incubation at 95°C for 10 minutes and the crude digests were made
up to 250µl in TE buffer. 5µl aliquots of the digests were then used for HPV L1
consensus PCR amplification in 100µl reactions using the MY09/MY11 primers (Bauer
et al. 1992, Manos et al 1989). A 286bp human β-globin fragment was amplified
simultaneously in all samples to act as an internal PCR control. PCR-negative controls,
and HPV-positive (SiHa cells) and negative controls were run in each experiment.
10µl aliquots of PCR product were run on agarose gels, vacuum blotted onto
nylon membranes and immobilised by UV cross-linking. Membranes were hybridised
with a β-globin oligonucleotide probe, then with a generic HPV probe in order to
determine HPV positivity. The probes used were biotin-labelled and positive
hybridisation was detected using enhanced chemiluminecence. Samples found to be
HPV positive were dot blotted onto new membranes and hybridised with a series of
biotinylated type-specific probes including 6/11/42 (mixed), 16, 18, 26, 31, 33, 35, 39,
40, 45, 51, 52, 53, 54, 55, 56, 57, 58, 59, 73 (PAP238A),ME180, PAP88, PAP155,
PAP291 and W13B. Samples giving a positive signal with the generic probe but which
were negative on all dot blots were considered positive but untyped.
4.5 Data management and analysis
The study was completed in 1997 and the flow chart presents the number of women
available at various levels of the study (Figure 4).
A descriptive analysis of the baseline data of the area and the study population
was carried out. Representativeness of the compliant and non-compliant subjects was
studied with regard to known variables.
Prevalence of HPV was studied by variables grouped under the following
categories: socio-demographic factors, marital and reproductive factors, contraceptive
practices, symptoms at presentation, genital hygiene and sexual behaviour. The factors
considered under the socio-demographic category were age group, religion, monthly
income of the whole family, type of house, education of woman, occupation of husband
and tobacco chewing.
26

26.
Total women
in study area
15464
Married women
9320 (60.3%)
Non compliant
5264 (56.5%)
Complied
4056 (43.5%)
Individual questionnaire+Sexual Individual questionnaire only
behaviour questionnaire 1521 (37.5%)
2535 (62.5%)
Perished samples
Perished samples
113
77
HPV testing
3866 (95.3%)
2458 1408
Figure 4. Flow chart – HPV prevalence study in Trivandrum, Kerala, India, 1995–1997.
Socio-economic status of the woman was not clearly evident from these variables.
An index of socio-economic status (SES) was generated by combining the different
levels of the factors, ‘monthly income’, ‘education of woman’ and ‘husband’s occu-
pation’. Based on these combinations, three levels of (low, middle and high) social class
were generated. This variable ‘SES’ was used for further analysis.
The category of marital and reproductive factors included age at menarche, age at
marriage, marital status (status of marriage at the time of interview), age at first
childbirth, total number of pregnancies, contraceptive methods and history of
vasectomy in husband. To obtain the time between the onset of menarche and age at
marriage, a new variable was generated by calculating the difference in years between
the age at marriage and age at menarche. This variable had three levels, <6 years
difference, 6–10 years and >10 years. Instead of age at menarche and age at marriage,
this variable (menarche-marital difference) was used for further analyses.
27

27.
Contraceptive methods of woman and husband’s vasectomy were combined to
generate a new variable which had three levels; no contraception for husband and wife,
spacing methods and permanent sterilisation for husband and/or wife. This variable
‘contraception’ was used for further steps.
The factors included in the category, genital hygiene were ‘washing after coitus
by woman (W)’ washing after coitus by husband (H) and ‘intercourse during
menstruation’. The variables for husband and wife were considered together and the
new variable ‘genital hygiene (H&W)’ was used for further steps. This variable is a
representation of the hygienic practices of the couple.
The category sexual behaviour included the variables, husband’s premarital
partnerships (H), extramarital partnerships (H), husband’s visit to commercial sex
workers, wife’s premarital partnerships (W) and extra marital partnerships. These
variables reflected the sexual behaviour and hence were combined to generate two
variables. Promiscuity for wife, which classified the women as having had no premarital
or extra marital partners versus having had extra or premarital, partners (promiscuity
W). Similarly for men, the variable promiscuity (H) classified them as having had no
premarital, extra marital partners or visits to commercial sex workers versus those who
had any one of these contacts. These two variables were considered for further steps.
In each category the prevalence of HPV positivity is given along with the total
and HPV positive numbers in each level of the factor.
The determinants of HPV infection were studied by applying the logistic
regression model (Breslow and Day 1980). Logistic regression analysis have been
employed in similar situations to study the determinants (Coutlee et al. 1997, Jaakkola
et al. 1993, Makela et al. 1993). HPV infection was taken as the binary outcome.
Univariate analyses were carried out for each factor and the odds ratios and
corresponding 95% confidence intervals were presented. A multivariate analysis was
done within each category and adjusted for the variables within that category and for
age. The adjusted odds ratios and 95% confidence intervals are also presented in the
tables. All the analyses were done with the software SPSS (SPSS for windows 9.0).
The variables which were statistically significant, or those which were considered
relevant, were carried forward. The final model was constructed with the variables thus
selected from each category and they were adjusted against each other and for age in a
multivariate analysis. Interactions among the variables in this model were tested and
there were no significant interactions and hence are not presented. The final model
identified the independent determinants of HPV infection.
28

28.
5 RESULTS
5.1 Total population
The study area had a total (men 14,966 and women 15,464) population of 30,430,
spread over eleven wards in Kazhakuttom Panchayat and Maryanadu village. From the
analysis of the data from the household questionnaire, age and gender distribution, and
distribution by religious groups of the community were generated.
Age and gender distribution
The age structure of Kerala State (Figure.5) and the study area (Figure.6) are given
below. The younger ages (base of the pyramid) are receding with a trend towards an
expansion in the middle.
Figure 5. Kerala population by age and Figure 6. Kazhakuttom & Maryanadu popu-
sex (1996). lation by age and sex (1996).
29

29.
The male to female ratio was 1033 women for 1000 men. The sex ratio for the
State of Kerala was 1036 women for 1000 men (Economic Review 1996)
Distribution by religion
The distribution (%) of religious groups in the study area and in the State of Kerala is
presented in Figure 7. The majority of the population belong to Hinduism and there was
an almost equal proportion of Christians and Muslims.
80 Study area
70 Kerala
60
50
40
30
20
10
0
Hindu Muslim Christian
Figure 7. Distribution (%) by religion, Study area and Kerala State, 1995.
5.2 Eligible women
From the baseline survey, all married women who were permanent residents of the area
were identified and were considered as eligible women (n = 9320). Table 2 presents the
female population, number of eligible women and those who participated in the study
by age group.
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31.
Non compliant
Compliant
100 %
90 %
80 %
70 %
60 %
50 %
40 %
30 %
20 %
10 %
0%
Ward (MD Maryanadu)
Figure 8. Compliance with screening by area of residence, Trivandrum HPV study.
Compliance by religion
Compliance to the invitation was compared among the different religious groups. The
compliance among Hindus was 46%, Muslims 38% and 36% among Christians.
5.4 Characteristics of the study participants
Characteristics of the four thousand and fifty six (4056) women who had complied with
the study through the data collected by the personal interview are presented.
5.4.1 Socio-demographic variables
Type of house
Twenty percent of people lived in concrete houses and 49.7% were in thatched houses.
Thatched houses are built with mud and the roof is made of coconut leaves. The rest
were living in tiled houses.
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32.
Educational status
The distribution (%) of educational status of the 4056 women is given in Figure 9. Only
15% of the study population were illiterate. A good proportion of women had been to
high school (23.9%) and university (6.2%).
University
High School
Middle School
Primary School
Illit/Minimal
0 5 10 15 20 25 30
Figure 9. Women's educational status in Trivandrum HPV study, 1995–1997.
Occupation of women
The women were mostly housewives even though they were educated. Ninety percent
of the women were housewives, 6.9% manual labourers and 2.6% had office jobs. In
Maryanadu, the fishing village, 78% were housewives and 22% were manual labourers.
Occupation of husband
Occupation of the husbands of the participants was asked and categorised (Figure10).
Forty five percent of the husbands were manual labourers. Working in countries around
the Persian Gulf is becoming increasingly common and 8.8% of women had husbands
working in one of the Gulf countries.
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33.
Military/Police
Nil
Employed outside the
country
Others
Merchant
Govt servant
Manual labourer
0 5 10 15 20 25 30 35 40 45 50
Figure 10. Occupation of husbands of study subjects in the Trivandrum HPV study 1995–97.
Monthly income
Many men were not on fixed salaried jobs and an overall income of the family per
month was collected in Indian Rupees (1US $ = 43 Indian Rupees). There was some
reluctance to give the correct amount and the information from the wife may not always
have been correct. Majority of the women (64.9%) said that they were in the low
income category of less than 1000 Rs per month. Only 7.3% women were in the high
income category.
Tobacco and alcohol habits
Tobacco habits were enquired in the questionnaire. Information on tobacco chewing,
smoking and alcohol consumption were collected. Thirty one women (0.7%) reported
tobacco smoking and this was mainly seen in the older age groups. The mean age of
tobacco smokers was 58.2 yrs (SD 8.62). All women who smoked tobacco, used bidi (a
locally made cigarette consisting of tobacco rolled in a dried leaf). Table. 3 presents the
distribution by chewing habit of women.
Tobacco chewing was practised as pan chewing, which consists of betel leaf,
tobacco, shell lime and areca nut. The median number of pan chewings per day was 4
with a range from 1 to 25 times. Only 3 women chewed 25 times a day. The average
duration of pan chewing was 11.2 years. None of the 4056 women reported alcohol
consumption.
34

34.
Table 3. Tobacco chewing habits among the study subjects in the Trivandrum HPV study 1995–1997.
__________________________________________________________________________
Tobacco chewing n %
__________________________________________________________________________
Not habituated 3388 83,5
Current habituees 625 15.4
Past habituees 43 1.1
Total 4056
__________________________________________________________________________
5.4.2 Reproductive and marital history
Marital status
Status of married life at the time of the study was asked and information was available
on 4032 women (Figure11).
4%
6% Living with husband
7%
Separated
Temp living separately
Widowed
83 %
Figure 11. Status of marriage of the women in the Trivandrum HPV study.
Age at menarche
The median age at menarche was 14 years. ( Mean 14.4 and SD 1.5). Sixty four percent
of the women had menarche between the ages 14 and 16 years.
35

35.
Age at first marriage
The median age at marriage was 20 years for the women who came into the study.
Information was not available on 18 women.
Age at first childbirth
Of the total of 4056 women, 3911supplied information on age at first child birth, while
it was unavialable in 28 women. One hundred and seventeen women had only three
years of married life and were not considered for this variable. The median age at first
childbirth was 21 years and this represents the usual practice of having the first child
within one year after marriage.
Total pregnancies
Ninty nine women had no live birth at the time of interview (18 women did not provide
the information). Forty six percent of the women had 3 to 5 pregnancies.
Age at menopause
Eight hundred and twenty six women (20.3%) had attained menopause at the time of the
study. Exact age at which menopause attained was available for 401(48.5%) women.
The median age of attaining menopause was 46 years.
The distribution of the study subjects in the various strata by these variables are
presented in Table 4.
36

36.
Table 4. Distribution by marital and reproductive factors of women in the Trivandrum
HPV study 1995–97.
_____________________________________________________________________
Marital and reproductive factors n %
_____________________________________________________________________
Age at menarche
< 14 yrs 1100 27.1
14–16 yrs 2602 64.2
> 17 yrs and above 354 8.7
Total 4056
Age at first marriage
< 20 yrs 1964 48.4
20–24 yrs 1689 41.6
25+ 385 9.6
Not available 18 0.4
Total 4056
Age at first childbirth
< 20 yrs 1126 28.8
20–24 2126 54.4
25+ 659 16.8
Total 3911
Age at menopause
30–39 yrs 19 2.3
40–49 yrs 290 35.1
50–59 yrs 92 11.1
Age not known 425 51.5
Total 826
Total pregnancies
0 99 2.4
1–2 1660 41.1
3–5 1877 46.4
5+ 402 10.0
Total 4038
_____________________________________________________________________
Contraceptive practices
Contraceptive practices of the women were collected through the interview. Information
was available on 4026 women. Women were also asked about vasectomy for husbands.
Temporary contraceptive practices among the 1131 women in the age group below 50
yrs is presented in Table 5.
Permanent sterilisation was the most common method among women. Two
thousand three hundred and forty four women had tubectomy. The prevalence of
permanent sterilisation was studied by year of birth. The exact age at sterilisation was
not available. Figure 12 presents the proportion of women with permanent sterilisation
by year of birth.
Ninety three (2.3%) women reported that their husbands had had a vasectomy, of
these 88 women had no contraception, one had a coil (intrauterine contraceptive device)
and 4 had sterilisation.
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38.
Post coital bleeding
Post menopausal bleeding
History of STD
Irregular bleeding
Low back pain
White discharge P/V
0 5 10 15 20 25
Percentage
Figure 13. Prevalence of gynaecological symptoms in the Trivandrum HPV study 1995–97.
5.4.4 Genital Hygiene and sexual behaviour
Two thousand five hundred and thirty five women (62.5% of the compliant women)
were interviewed for sexual behaviour and genital hygiene. The questionnaire for these
variables were introduced one year into the study and the interviewed do not form a
sample. Hence the chance factor is not tested between the groups. Moreover, with such
large numbers even very small differences will emerge siginificant. A comparison of
those who were interviewed against those who were not interviewed, by selected
variables is given in Table 6. The groups are comparable with respect to the variables
studied.
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40.
Table 7. Genital hygienic practices (Yes/No) among men and women in the Trivandrum HPV study
_____________________________________________________________________
Woman Husband n %
_____________________________________________________________________
Yes Yes 2344 94.4
Yes No 36 1.5
No Yes 3 0.1
No No 100 4.0
_____________________________________________________________________
Total 2483
_____________________________________________________________________
Pre marital and Extramarital relationships
Extramarital and premarital sexual behaviour of the women and their spouses were
enquired. Out of the 2535 women who answered the sexual history questionnaire, the
information could not be gathered from 56 women on extra marital relationships of
husband, leaving 2479 in the Tables 8 and 9.
Six hundred and ninenty six (28%) women reported that their husbands had
partners prior to marriage. Five hundred and fifty seven (22.4%) women reported that
their husbands had had extra marital partners. Five hundred and twenty three (21.1%)
women reported that their husbands visited commercial sex workers. The responses
given by the wives were compared (Table 8). Association between the statements of the
wife regarding premarital and extramarital partners for husband was high, (κ = 0.82).
Table 8. Association between premarital and extramarital partners for husband.
_____________________________________________________________________
Extramarital partner Premarital partner
No Yes Total
_____________________________________________________________________
No 1768 154 1922
Yes 15 542 557
_____________________________________________________________________
Total 1783 696 2479
_____________________________________________________________________
Table 9. Association between husband’s extramarital partners and visiting commercial sex workers
_____________________________________________________________________
Extramarital partner Commercial sex worker
No Yes Total
_____________________________________________________________________
No 1879 43 1922
Yes 77 480 557
_____________________________________________________________________
Total 1956 523 2479
_____________________________________________________________________
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41.
There was a high association between the responses of the wife regarding
extramarital partners and visit to commercial sex workers by husbands (κ = 0.85) (Table
9).
Premarital and extramarital partners for wives were asked and the association
between the responses are given in Table 10.
Sixty two (2.4%) women reported having had partners prior to marriage. Thirty
four (1.3%) women reported having extra marital partners. The association of the
responses for premarital partner and extramarital partner of the wife was moderate (κ =
0.59).
Table 10. Association between premarital and extramarital partner for wife
_____________________________________________________________________
Premarital partner Extra marital partner
No Yes Total
_____________________________________________________________________
No 2468 5 2473
Yes 33 29 62
_____________________________________________________________________
Total 2501 34 2535
_____________________________________________________________________
5.5 Prevalence and determinants of HPV infection
HPV prevalence was studied from the 3866 women whose samples were analysed by
PCR. The results of the PCR tests done in the Institute of Cancer Research Laboratories
in Sutton, UK, were linked to the database and prevalence by various characteristics of
the women were generated. The prevalence for HPV all types has been described in all
the tables. The characteristics were broadly grouped as socio-demographic, marital and
reproductive factors, contraceptive practices, symptoms at presentation, genital hygiene
and sexual behaviour.
5.5.1 Prevalence by age
The age specific prevalence of HPV is given in Figure 14. The age specific prevalence
at 4 points and the 95% confidence intervals for the prevalence rates are plotted. The
overall prevalence of all ages (234/3866) was 6.1% (95% CI 5.3–6.8). The tests for
linear trend (p = 0.7) and for heterogeneity (p = 0.84) were non significant.
42

42.
10,00
9,00
8,00
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
<30 30-44 45-59 60+
Age group
Figure 14. Prevalence rate & 95% CI of HPV (all types) by age group in the Trivandrum HPV study,
1995–97.
5.5.2 Socio-demographic variables.
Prevalence of HPV, crude and adjusted odds ratios for the various socio-demographic
factors are presented in Table 11.
Muslim women had the least prevalence of 4.1% compared to Christian and
Hindu women. Low income group and low socio-economic groups had a higher
prevalence compared to lower income groups. When adjusted for each other, socio-
economic status emerged as significant and religion had borderline significance (p =
0.06). However Muslims had a significantly reduced risk.
5.5.3 Marital and reproductive factors and contraceptive practices
Prevalence of HPV, crude and adjusted odds ratios and corresponding 95% confidence
intervals for marital and reproductive factors and contraceptive practices are presented
in Table 12.
The prevalence was very low (2.9%) in those who practised barrier
contraceptives. History of vasectomy for husband resulted in a prevalence of 5.5%.
Permanent sterilisation of either husband or wife did not have an effect on the
prevalence rates. Age at first childbirth was correlated with the variable menarche-
marriage difference (Spearman correlation coefficient 0.7) and hence was not included
in the multivariate model. None of the factors attained statistical significance in this
group.
43

45.
5.5.4 Symptoms at presentation
Prevalence of HPV, crude and adjusted odds ratios and corresponding 95% confidence
intervals for symptoms at presentation are presented in Table 13. Women who had
postmenopausal bleeding had a prevalence of 15.4% compared to 6.0% for those who
did not have this symptom. However, this was based on only 2 HPV positive women.
Presence or absence of symptoms of white discharge p/v and irregular bleeding p/v did
not show any appreciable change in the prevalence. Women with history of any sexually
transmitted disease had 7.1% prevalence compared to 6% among those who did not
have such a history. None of the variables studied under this category attained statistical
signficance.
Table 13. HPV prevalence, crude and adjusted odds ratios and 95% confidence intervals by symptoms at
presentation in the Trivandrum HPV study.
______________________________________________________________________
Factor Total HPV+ Crude Adjusted1
% (n) OR 95% CI OR 95% CI
______________________________________________________________________
White discharge p/v
No 3111 6.1 (191) 1.00 1.00
Yes 755 5.7 ( 43) 0.92 0.65–1.29 0.88 0.62–1.27
P.M bleeding p/v
No 3853 6.0 (232) 1.00 1.00
Yes 13 15.4 ( 2) 2.83 0.62–12.87 3.13 0.67–14.46
Irregular bleeding p/v
No 3725 6.1 (226) 1.00 1.00
Yes 141 5.7 ( 8) 0.93 0.45–1.92 0.90 0.43–1.89
History of any STD
No 3725 6.0 (224) 1.00 1.00
Yes 141 7.1 ( 10) 1.19 0.61–2.30 1.29 0.65–2.56
______________________________________________________________________
Adjusted1 for variables in the table and for age. The variable contraception is generated out of the
variables contraceptive methods for wife and vasectomy for husband and hence these two variables were
not included.
P.M.-Post menopausal
5.5.5 Genital hygiene
Prevalence of HPV, crude and adjusted odds ratios and corresponding 95% confidence
intervals for genital hygiene related variables are presented in Table 14. The two
variables, washing habits of husband and wife were highly correlated [Correlation
46

46.
between washing habit of wife and husband – Spearman Correlation Coefficient 0.872
(p<0.0001)]. A variable genital hygiene for husband and wife (H&W) was generated by
combining the variables collected in separate questions. The prevalence was very high
in women who did not practise genital hygiene (20.3% compared to 7.8%). Women
when they themselves and their husbands did not practice genital hygiene had a
prevalence of 24% compared to 7.3% for those who practised hygiene. The variable
genital hygiene of husband and wife was considered as the representative variable and
used in the multivariate model. The adjusted odds ratio was significant for genital
hygiene (H&W) when adjusted for age and coitus during menstruation.
Table 14. HPV prevalence, crude and adjusted odds ratios and 95% confidence intervals by genital
hygiene in the Trivandrum HPV study (n = 2458).
______________________________________________________________________
Factor Total HPV+ Crude Adjusted1
% (n) OR 95% CI OR 95% CI
______________________________________________________________________
Washing after coitus (W) #
Yes 2315 7.8 (181) 1.00 n.i.
No 143 20.3 ( 29) 2.90 1.94–4.63
Washing after coitus (H) #
Yes 2281 7.3 (167) 1.00 n.i.
No 177 24.3 ( 43) 4.06 2.78–5.92
Genital Hygiene (H&W) # #
Yes 2278 7.3 (167) 1.00 1.00
No 180 23.9 ( 43) 3.96 2.72–5.78 3.97 2.60–6.10
Coitus during
menstruation #
No 2306 8.1 (187) 1.00 1.00
Yes 152 15.1 ( 23) 2.02 1.26–3.22 1.37 0.83–2.27
______________________________________________________________________
Adjusted1 for variables genital hygiene of H&W, coitus during menstruation and age.
# Significant (p<0.05); n.i – Not included
5.5.6 Sexual behaviour
Prevalence of HPV, crude and adjusted odds ratios and corresponding 95% confidence
intervals for sexual behavioural factors are presented in Table 15. Women whose
husbands had pre marital sexual partners had a prevalence of 10.2% compared to 7.9%
for those who did not have that history. Promiscuity for wife resulted in a prevalence of
24.2% and women whose husband’s were promiscuous had a prevalence of 10.2%.
Univariate analysis produced odds ratios which were significant for husband’s and
wife’s promiscuity. These two variables and age were studied in a multivariate model
and promiscuity for wife emerged as the significant factor.
47